Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon.
The semiconductor industry continues to improve the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) by continual reductions in minimum feature size, which allow more components to be integrated into a given area. These smaller electronic components also require smaller packages that utilize less area than packages of the past, in some applications.
Static Random Access Memory (SRAM) is chosen as a reliable, proven technology for high-performance stand-alone memory devices or embedded memory devices. The advantages of an SRAM include fast access speed, low power consumption, high noise margin, and process compatibility with a CMOS fabrication process. However, there are many challenges related to fabricating SRAM.